From: Caleb Clausen <vikkous@...>
Date: 2006-08-03T06:44:42+09:00
Subject: Re: Building the finite state machine of a Ruby regexp

On 8/1/06, Gilles Lacroix <lacroix7@free.fr> wrote:
>
> Does anyone know if there is a nice way to build the Finite State Machine
> (FSM) of a Ruby regexp ?

I don't know of anything specifically oriented to Ruby Regexps that
does this, but surely such tools exist for (say) Perl...?

> As an alternative solution, I wonder if someone knows about a module that
> could parse Ruby regexps (accepting exactly the same regexp grammar as
> Ruby) and let me read the associated FSM (or whatever graph-like structure
> representing the regexp).

Given how notoriously opaque they are, I've actually found regular
expressions to be pretty easy to parse. I can send you a partial
Regexp parser from one of my projects that just extracted the
information I needed to know at the time.... but probably what you
really want is Simon Strandgaard's regexp-engine. You can find it
here:

http://rubyforge.org/projects/aeditor/